1. Field Of The Invention
The present invention relates to an improved dynamic tooth clutch interposed between a rotating first member, operating at a first speed, and a rotating second member operating at a second speed. This invention may be utilized, for example, as a differential lock structure in a differential mechanism. The dynamic tooth clutch, by having one of its toothed portions attached to an axle shaft and the other of its toothed portions attached to the differential case, by utilizing the improved cam ring of this invention together with the improved tooth structure, prevents corner hang-up.
2. Description Of The Prior Art
The prior art is replete with locking differential structures, examples thereof being shown in U.S. Pat. No. 1,888,884 to Omer et al, U.S. Pat. No. 2,304,914 to Hibbett, U.S. Pat. No. 2,803,149 to Pringle, U.S. Pat. No. 2,876,658 to McColl, and U.S. Pat. No. 3,498,154 to Mueller-Berner, with many of these structures utilizing jaw-type or toothed-type clutches. While these prior art structures tend to perform quite satisfactorily, a problem has remained in that the use of tooth-type clutches generally require that the engaging and disengaging sequences are preferably performed while the vehicle is at rest since the lack of synchronizer mechanisms causes clashing during dynamic conditions. In addition, if there is but partial axial engagement between the opposing clutch teeth, extremely high tooth shock loadings as well as possible tooth shear can result. Such partial engagement between the clutch teeth can, of course, readily result since there may be a speed differential of up to several hundred r.p.m. between the axle shaft and the differential case, for example.
Co-pending application Ser. No. 561,520, filed Mar. 24, 1975, now U.S. Pat. No. 3,973,450, discloses therein a dynamic tooth clutch which solves many of the previously-noted problems in that it utilizes a cam ring that is capable of a predetermined amount of bidirectional angular rotational movement relative to one of the clutch halves, with this angular displacement allowing full centered intermeshing of the main torque-transmitting teeth before there is abutment and subsequent torque transfer between either of the side surfaces of one of the sets of teeth with the adjacent side surfaces of the other set of teeth.
The dynamic tooth clutch disclosed in said co-pending Application is interposed between two rotating members for coupling same and includes a first collar slidably mounted on one of the members, with this first collar having a plurality of equally angularly spaced axially extending radial first inner and outer teeth. A second collar is fixed to the other member and has a plurality of equally angularly spaced axially extending radial second outer teeth that are designed to intermesh with the first outer teeth and are so angularly spaced that when the first and second outer teeth are centered relative to one another there can be a first predetermined amount of bidirectional angular rotational movement therebetween before there is abutment of adjacent tooth side surfaces. A cam ring coacts with the second collar, with the cam ring being capable of a predetermined amount of bidirectional angular rotational movement relative to the second collar. The cam ring, which is preloaded and self-centered relative to the second collar, has a plurality of second inner teeth that are angularly aligned with the second outer teeth in the self-centered cam position, with the combined tooth depth of the first and second inner teeth being greater than the combined tooth depth of the first and second outer teeth, thus permitting axial end abutment of only the inner teeth in the absence of intermeshing. The force for displacing the first collar toward the second collar is less than the centering force on the cam ring thus permitting direct meshing of the first and second inner teeth but only complete centered axial meshing of the first and second outer teeth prior to the angular displacement of the cam ring relative to the second collar, thereby allowing full axial intermeshing of the first and second outer teeth before there is abutment and subsequent torque transfer between the outer teeth.
While the invention disclosed in said co-pending Application is effective for carrying out the objectives thereof, a considerable amount of further investigation has been carried out related thereto, both for simplifying of the structure itself and for improving the operation thereof.
In this last connection, it was noted in the further development of the collar members that the intersections of the tooth axial end faces and the tooth side surfaces, i.e., the corner intersections, of the first and second inner teeth, will on occasion hang-up. Thus, rather than frictionally sliding relative to one another, the opposing inner teeth hang-up on a corner, with this hang-up causing the angular translation of the cam ring. However, since there is no intermeshing of either the opposing inner and/or outer teeth, the cam ring will be angularly displaced but after a limited (5.degree. ) movement its external splines will encounter the internal splines on the second collar, with this encounter producing spline breakage and subsequent serious damage to the clutch structure. Basically, the structure of said co-pending Application has no mechanism for alleviating this corner hang-up problem.
One primary object of the present invention is to provide a dynamic tooth clutch having means for solving the previously-described corner hang-up problem. A further primary object of the present invention is to provide for complete axial engagement of the collar teeth before there is abutment and subsequent torque transfer between the adjacent side surfaces of the collar teeth. In addition, in a continued effort to still further improve upon the above-described dynamic tooth clutch, particularly in an effort to find other variations thereof relative to increasing the amount of angular rotational movement of the opposed collars relative to one another before there is actual tooth engagement, still further variations have been made in the cam ring structure which are particularly suitable for use in the dynamic tooth clutch to improve the operation thereof.